The reception of satellite programmers with a personal dish at individual home.
DTH does not require the local cable operator and put the broadcaster directly in touch with the consumer.</li></li></ul><li> WHAT IS DTH<br /><ul><li>DTH Stand’s for Direct to home television .</li></li></ul><li><ul><li>HISTORY
The first person who invented the technology for DTH was sir ARTHURE CLARLES CLARKE , a british inventor in late 1946.
The DTH service was first proposed in INDIA in 1996 , but was not approved due to concern over national security.
Finally , 2000 DTH service was allowded and Doordarshan was first to </li></li></ul><li><ul><li>To provide the service to the consumers from 1st of April ,2000.
After this other DTH service provider like ZEE and STAR starded pushing hard for DTH service in INDIA and setup earth station whose cost was 2.15 million and was valid for 10 years in INDIA.</li></li></ul><li><ul><li> MAIN PARAMETER OF DTH
Uplink satellite dishes are large in size which provides accurate aiming and increase signal strength
The y are pointed toward specific satellite and the frequency used is specific so that satellite transponder can receive the signal. </li></li></ul><li><ul><li>The EIRP (Effective isotropically radiated power) for the uplink antenna </li></ul>EIRP = Pt – Lc + Ga<br />Where <br />Pt = Power of transmitter (dbm)<br />Lc = Line loss(db)<br />Ga = Gain of antenna(dbi)<br />
A typical satellite can have 32 transponder for Ku band (10 Ghz to 18 Ghz) and 24 transponder for C band( 4 Ghz to 8 Ghz).
A typical transponder can have bandwidth between 27 Mhz to 50 Mhz.
The satellite retransmits the signal back to earth in Ku band and C band frequency.</li></li></ul><li><ul><li>MINIDISH ANTENNA
It is parabolic reflector it receives the signal and fed to the LNBF(low noise band down converter) ,which works as a receiver for signal transmitted by satellite.</li></ul>LNBF<br />Parabolic reflector<br />( 60 to 120 cm )<br />
<ul><li>SIGNAL RECEIVED BY MINIDISH</li></li></ul><li><ul><li>LOW NOISE BLOCK DOWN CONVERTER(LNBF)
The coaxial cable connect LNBF to set top box.
A transmission cable consist of outer metal condutor enclosing and insulated from a central conduting core.</li></li></ul><li><ul><li>Impedance provided by the coaxial cable</li></ul>can be calculated by the formula<br />Z0 =( 1/2∏)√μ/ εln(D/d)<br />Where<br />μ = relative permeability of inisulator<br /> ε = dielectric constant <br />D =outer diameter of the coaxial cable<br /> d = inner diameter of coaxial cable.<br />
<ul><li>A settop box can demodulate the received signal and can convert these signal into audio and video signal.
SETTOP BOX</li></li></ul><li><ul><li>SET TOP BOX
GENERAL BLOCK DIAGRAM OF SETTOP BOX </li></ul>DISH ANTENNA<br />A<br />DECODER<br />AMPLIFIER<br />TUNER<br />DEMODULATOR<br />V<br />MICROCONTROLLER<br />CAS SYSTEM<br />
<ul><li>TUNNER</li></ul>It select particular channel range from 48 Mhz to 840 Mhz<br /><ul><li>DEMODULATOR</li></ul>Selected channel demodulated and fed to decoder<br /><ul><li>DECODER</li></ul>It is a D to A converter which provide audio and video signal as output.<br /><ul><li>MICROCONTROLLER</li></ul>It control all the process performed by each block.<br />
In DTH , TV channel are directly transmitted from satellite to a small dish antenna at the subscriber home.
The broadcaster directly connect to the subscriber ,the middlemen like local cable operator are not there in the picture , hence provide better picture quality directly from satellite to the user. </li></li></ul><li><ul><li>The cable TV was limited to the urban area ,but the DTH followed cable TV in urban as well as in rural area.
DTH technology is more resistive to the weather condition ,it can work in any type of environment.
Since coaxial cable connection are used in DTH technology less distortion of the signal take place , which ultimately provides better picture quality and better signal.</li></li></ul><li><ul><li>FUTUTRE PROSPECT OF DTH
The DTH market in INDIA is relatively incresing day by day and in next 5 years (by 2014 ) we will be able to add another 30 million subscriber.
In the next 5 years ..,we have manage to overtake JAPAN as the largest DTH market in ASIA.</li></li></ul><li><ul><li>DTH SERVICE PROVIDER</li></li></ul><li><ul><li>CONCLUSION
DTH has made the hopes for people of the rural area to come true.
It help to develop the economy condition of our country
It provide the wide thinking of rural people which helps to develop the culture of society. </li></li></ul><li>